The present invention relates to an inlet type noise filter and, more particularly, to an inlet type noise filter which can be mounted directly on a mounting substrate or the like.
The conventional inlet type noise filter, as shown in FIGS. 10 and 11, has an inlet socket 11 mounted on a rectangular casing 13. A bayonet portion 12 of the socket 11 is disposed over an open end of the casing 13 so as to be exposed at the exterior of the casing. A filter circuit (not shown) comprising inductors and capacitors forming an equivalent circuit as shown in FIG. 12 is provided at the rear side of the socket 11 and lug-shaped output terminals 14 and 15 and a ground terminal 16 are fixed on the surface of the casing 13 that extends perpendicular to the open end of the casing.
In addition, the output terminals 14 and 15 are fixed onto thick projections 17 and 18 formed on the surface extending perpendicular to the open end.
The conventional inlet type noise filter constructed as described above, as shown in, for example FIG. 13 is mounted on a box 21 of an electric instrument or the like with the bayonet portion 12 exposed and with the terminals 14, 15 and 16 electrically connected with a printed substrate 22 through lead wires 23, 24 and 25, respectively.
Such a conventional inlet type noise filter is mounted by performing complicated connection work, and is subject to a problem in that the noise produced within the box 21 is distributed to the lead wires 23, 24 and 25 thereby diminishing the filter function of the noise filter.
When the noise filter is intended to be mounted directly on the printed substrate in order to solve the above-mentioned problem, the casing 13 of the noise filter is not flat but is stepped at the surface on which the terminals are fixed and through which the casing 13 is attached to the box 21, thereby resulting in inconvenience in that the filter cannot stably be mounted on the box 21.